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Abstract Metal‐free carbon‐based catalysts have attracted significant attention owing to their unique electronic structure and excellent catalytic activity for the oxygen reduction reaction (ORR). Recently, several heteroatom‐doped carbon catalysts with ORR performances comparable with those of state‐of‐the‐art Pt‐based catalysts have been reported. However, the intrinsic influence of heteroatoms on the catalytic activity has not been thoroughly investigated to date. This paper reports porous carbons co‐doped with N and S, prepared using an ion‐exchange resin and tetramethylammonium cations, with an onset potential of 0.93 V versus reversible hydrogen electrode (RHE) and a half‐wave potential of 0.79 V versus RHE. First‐principles calculations reveal that the change in the atomic charge caused by the co‐doping of N and S is important for inducing a high ORR activity. This paper presents a rational synthetic strategy for metal‐free catalysts and provides fundamental insights into their electrocatalysis.

The performance of CO2-expanded hexane in the vapor-liquid two-phase region was examined to extract phosphorus-free bio-oil from rice bran. Previously, it was found that in the uniform liquid phase region, it is difficult to maintain the phosphorus concentration at a stable and low level when the CO2 mole fraction changed slightly. To overcome this issue, the dependences of the phosphorus and free fatty acid concentrations, the oil solubility, and the oil yield on the CO2 mole fraction in the CO2-expanded hexane were measured at 25 °C, 5.1–5.2 MPa, and at a CO2 mole fraction of 0.88–0.94 in the two-phase region. Thus, a relatively constant phosphorus concentration of 2 mole fractions. Moreover, the oil solubility in the CO2-expanded hexane decreased linearly with the CO2 mole fraction, and so this factor represented the oil-dissolving power of the extractant more accurately than the oil yield used previously. The free fatty acid concentration was 83% of that extracted by hexane.

OSDA/solvent-free synthesis of zeolites is suitable for practical commercialization due to low environmental damage and low cost. However, only a few types of zeolites have been successfully synthesized by this method. In this study, ANA, CAN, GIS, SOD, FAU and LTA type zeolites were synthesized by the OSDA/solvent-free synthesis method by changing the Si/Al ratio and crystallization temperature in detail. At higher Si/Al ratios, FAU, GIS and ANA type zeolites were obtained with an increase of crystallization temperature. Meanwhile, at lower Si/Al ratios, LTA, SOD and CAN type zeolites were obtained with an increase of crystallization temperature. It was found that zeolites with high T atom density were synthesized with an increase of the crystallization temperature; zeolite with a high T atomic density is more stable. This work reveals the correlation between the Si / Al ratio and the crystallization temperature in OSDA/solvent-free synthesis of zeolites, which provides a clear guideline for the OSDA/solvent-free synthesis of zeolites. [ABSTRACT FROM AUTHOR]

Binary diffusion coefficients D12and retention factors kof ferrocene and 1,1′-dimethylferrocene at infinite dilution in supercritical (sc) carbon dioxide were measured by the chromatographic impulse response (CIR) method at temperatures from (308.2 to 323.2) K over a pressure range from (8.0 to 40.3) MPa for ferrocene and from (8.2 to 40.1) MPa for 1,1′-dimethylferrocene. The D12data for ferrocene were also measured by the Taylor dispersion method with two injection procedures of ferrocene: ferrocene dissolved both in sc CO2and in liquid hexane. The D12values of ferrocene were not affected by the injection methods and agreed with those measured by the CIR method. As has been seen for various organic compounds measured in our previous reports, the D12data for both metal complexes were correlated with the hydrodynamic equation D12/T= αηβ, where η is the CO2viscosity and α and β are the constants determined by each solute. The retention factors were also correlated with CO2density. [ABSTRACT FROM AUTHOR]

There is an urgent need to develop low cost electrochemical sensors wherein the sensor can be disposed after recording data, thereby eliminating the issue of inaccuracy arising from repeated sensing measurements, which plagues most conventional electrochemical sensors. This work is the first demonstration of a NiSe2 based disposable, one time use electrochemical glucose sensor in bio-mimicking real samples wherein NiSe2 was hydrothermally grown NiSe2 on a biodegradable cellulose paper. Both physicochemical (x-ray diffraction, x-ray photoelectron spectroscopy, field emission scanning electron microscope) and electrochemical (impedance spectroscopy and cyclic voltammetry (CV)) characterization techniques confirmed the growth and presence of NiSe2 on a cellulose paper. Electrochemical techniques like CV and amperometric (i–t) were utilized for the selective and sensitive oxidation of glucose. The results suggests that the proposed NiSe2 sensor is effective in a linear range of 0.1–1 mM with fast response time (3.9 s), low detection limit (24.8 ± 0.1 μM) and high sensitivity (0.25 A M−1 cm−2) at a potential applied (Eapp = 0.55 V versus Ag∣AgCl). Prior to the real sample analyses i.e. glucose detection in human urine, the fabricated NiSe2 sensor was tested for selectivity towards glucose in co-existing interferences (dopamine, ascorbic acid, uric acid, urea, sodium chloride, fructose, lactose and cysteine). Finally, glucose in artificial blood serum and urine samples was demonstrated with the fabricated NiSe2 sensor and the results are comparable to the conventional laboratory methods. The present methodology presents a novel possibility towards the design of next generation, affordable point-of-care devices for a broad range of clinical diagnostics. [ABSTRACT FROM AUTHOR]